Purpose: To evaluate prospectively the use of magnetic resonance (MR) imaging for differentiating true rheumatoid arthritis (RA) from systemic lupus erythematosus (SLE) or primary Sjögren syndrome in patients who have inflammatory polyarthralgia of the hands but no radiographic evidence of RA.
Materials and methods: This study had institutional review board approval, and patient informed consent was obtained. Twenty-eight patients (16 female and 12 male patients; mean age, 42 years) with early RA and 19 patients (18 female and one male patient; mean age, 46 years) with SLE (n = 14) or primary Sjögren syndrome (n = 5) underwent MR imaging of both hands. All patients had inflammatory polyarthralgia of the hands and no evidence of erosive changes on radiographs. Coronal T2-weighted short inversion time inversion-recovery, transverse T1-weighted spin-echo, transverse fat-suppressed gadolinium-enhanced T1-weighted spin-echo, and transverse gadolinium-enhanced three-dimensional gradient-echo MR images were obtained. The following MR imaging variables were assessed in the wrist and nonthumb metacarpophalangeal joints: synovitis, bone lesions (erosion, defect, and edema), and tenosynovitis. Synovitis and bone lesions were scored with the OMERACT RA-MRI scoring system. Findings in patients with RA and those without RA were compared by means of Mann-Whitney, chi2, and Fisher exact tests.
Results: The only significant difference between the two groups in terms of individual scores for synovitis, bone lesions, and tenosynovitis was the more frequent presence of tenosynovitis of the right fourth extensor tendon in patients without RA (P = .04). There were no significant differences between patients with RA and those without RA in terms of global scores for synovitis, bone lesions, and tenosynovitis. However, bone marrow edema in the metacarpophalangeal joints was seen more frequently in patients with RA (P < .001).
Conclusion: It may be impossible to distinguish between patients with early RA and those without RA (ie, those with SLE or primary Sjögren syndrome) by means of MR imaging.